Non-volatile memory devices are an important element of electronic systems due to their ability to maintain data absent a power supply. Ferroelectric random-access memory (FeRAM, FRAM) cells have been considered for use in non-volatile memory devices. Some non-volatile memory cells include ferroelectric materials exhibiting a switchable polarization responsive to application of an electric field (e.g., a bias voltage). Ferroelectric materials may include at least two polarization states, which polarization states may be switched by the application of the electric field. The polarization state of the ferroelectric material in a FeRAM cell may be used to determine a logic state (e.g., a 1 or a 0) of the FeRAM cell. After removal of the electric field, the polarization state of the ferroelectric material may remain stable for at least some period of time. Accordingly, the ferroelectric material may be suitable for use in a non-volatile memory device, eliminating the need to refresh the cell periodically.
Perovskite materials, such as lead zirconate titanate (PZT), have commonly been used as ferroelectric materials in FeRAM cells. However, such conventional ferroelectric materials often fall short in terms of bit density and scalability because perovskite materials exhibit low remnant polarization (Pr), a strength of which may correlate to a readout signal for the associated memory cell. For FeRAM cells, the thickness of the ferroelectric PZT film must be up to about 200 nm to achieve suitable properties since PZT loses its ferroelectric properties at lower thicknesses. Thus, the use of conventional ferroelectric materials for memory devices having a feature size of 20 nm or less has been limited. In addition, conventional ferroelectric materials, such as PZT, possess limited compatibility with standard semiconductor processing techniques.